Unexpected Reaction Course of 3-Amino-5-aryl-1<i>H</i>-pyrazoles with Dialkyl Dicyanofumarates
作者:Korany A. Ali、Eman A. Ragab、Grzegorz Mlostoń、Małgorzata Celeda、Anthony Linden、Heinz Heimgartner
DOI:10.1002/hlca.201200633
日期:2013.4
On treatment of 3‐amino‐5‐aryl‐1H‐pyrazoles 1 with dialkyl dicyanofumarates (=(E)‐but‐2‐enedioates) 4 in boiling 1,2‐dichloroethane, two competitive reactions occurred leading to 3‐aryl‐5‐cyano‐6,7‐dihydro‐6‐oxo‐1H‐pyrazolo[3,4‐b]pyridine‐4‐carboxylates 10 and 7‐amino‐2‐arylpyrazolo[1,5‐a]pyrimidine‐5,6‐dicarboxylates 11. In DMF at room temperature, as well as at 100°, only compounds 10 were isolated
在沸腾的1,2-二氯乙烷中用二氰基富马酸二烷基酯(=(E)-但是-2-烯二酸酯)4处理3-氨基-5-芳基-1 H-吡唑1时,发生了两个竞争反应,导致3-芳基- 5-氰基-6,7-二氢-6-氧代-1 H-吡唑并[3,4- b ]吡啶-4-羧酸酯10和7-氨基-2-芳基吡唑并[1,5 - a ]嘧啶-5, 6-二羧酸盐11。在室温以及100°C的DMF中,仅分离出化合物10。类型10的主要产品的形成通过将迈克尔加成1来合理化将C(4)-亲核试剂吸附到4上,然后消除HCN和内酰胺化。另一方面,次要产物11是通过经由NH 2基团在1至4上的迈克尔加成以及随后的HCN消除和环化而产生的。产品的结构已通过X射线晶体学确定。